Silica-based glass, such as soda-lime-silica glass, is prevalent in the manufacture of glass containers and other articles. Molten glass used to make such articles is conventionally prepared by melting a mixture of glass-forming materials known as a batch in one end of a continuous tank furnace. The resulting molten glass typically contains an undesirable amount of gas bubbles, commonly referred to as seeds. The gas bubble content of this unrefined molten glass is typically reduced to a desirable level by heating the molten glass to a relatively high temperature to reduce the viscosity of the molten glass so that gas bubbles within the molten glass can gradually rise to a free surface thereof and escape in a suitable amount of time. In such processes, rising convection currents within the molten glass are typically relied upon to bring the gas bubbles to the surface of the molten glass.
A general object of the present disclosure, in accordance with one aspect of the disclosure, is to provide an apparatus and a process for increasing the rate at which gas bubbles are released and/or removed from a flow of molten glass, as compared to conventional refining processes. The apparatus and process of the present disclosure also may reduce the temperature at which the molten glass must be heated to effectively refine the molten glass.
The present disclosure embodies a number of aspects that can be implemented separately from or in combination with each other.
In accordance with an aspect of the disclosure, there is provided a process for refining molten glass in which molten glass is provided that includes a plurality of gas bubbles. A porous body is also provided that includes an inlet, an outlet in fluid communication with the inlet, and a plurality of pores through which molten glass can flow between the inlet and the outlet. The plurality of pores of the porous body are defined by walls having wall surfaces. The molten glass is flowed through the porous body and through the plurality of pores such that interaction between the molten glass and the wall surfaces of the pores promotes release of gas bubbles from the molten glass, or causes at least some of the gas bubbles within the molten glass to collapse or rupture to reduce the size of the gas bubbles to a commercially acceptable size.
In accordance with another aspect of the disclosure, there is provided an apparatus for refining molten glass including an annular porous body having an inlet, an outlet in fluid communication with said inlet and spaced apart from said inlet in a radial direction, a plurality of pores through which molten glass can flow between said inlet and said outlet, and an effective porosity in the range of 0.75 to 0.95.
In accordance with another aspect of the disclosure, there is provided an apparatus for refining molten glass including a conduit having an inlet and an outlet and a longitudinal axis, and one or more porous bodies serially arranged within the conduit along the longitudinal axis thereof.